Makes GrGLProgramDesc's key store the lengths as well as offsets of the effect keys.

src/gpu/gl/GrGLProgramEffects.cpp

Index: src/gpu/gl/GrGLProgramEffects.cpp
diff --git a/src/gpu/gl/GrGLProgramEffects.cpp b/src/gpu/gl/GrGLProgramEffects.cpp
index 65d14fde116dc65f29f20ab426048583aa326ba1..9936aa54ad975897143549bc624a0272ebe25879 100644
--- a/src/gpu/gl/GrGLProgramEffects.cpp
+++ b/src/gpu/gl/GrGLProgramEffects.cpp
@@ -114,6 +114,27 @@ SkMatrix get_transform_matrix(const GrDrawEffect& drawEffect, int transformIdx)
 
 ////////////////////////////////////////////////////////////////////////////////
 
+bool GrGLProgramEffects::GenEffectMetaKey(const GrDrawEffect& drawEffect, const GrGLCaps& caps,
+                                          GrEffectKeyBuilder* b) {
+
+    EffectKey textureKey = GrGLProgramEffects::GenTextureKey(drawEffect, caps);
+    EffectKey transformKey = GrGLProgramEffects::GenTransformKey(drawEffect);
+    EffectKey attribKey = GrGLProgramEffects::GenAttribKey(drawEffect);
+    uint32_t classID = drawEffect.effect()->getFactory().effectClassID();
+
+    // Currently we allow 16 bits for each of the above portions of the meta-key. Fail if they
+    // don't fit.
+    static const uint32_t kMetaKeyInvalidMask = ~((uint32_t) SK_MaxU16);
+    if ((textureKey | transformKey | attribKey | classID) & kMetaKeyInvalidMask) {
+        return false;
+    }
+
+    uint32_t* key = b->add32n(2);
+    key[0] = (textureKey << 16 | transformKey);
+    key[1] = (classID << 16 | attribKey);
+    return true;
+}
+
 EffectKey GrGLProgramEffects::GenAttribKey(const GrDrawEffect& drawEffect) {
     EffectKey key = 0;
     int numAttributes = drawEffect.getVertexAttribIndexCount();